1. Technical Field
The present invention relates generally to an improved communications system and in particular to a method and apparatus for transferring within the communications system. Still more particularly, the present invention relates to an improved method and apparatus for managing a transfer of data from a source to a target in the communications system.
2. Description of the Related Art
In the transmission of data within a communications system from a source to one or more targets or destinations, broadcasting is a form of addressing wherein the destination address specifies all destinations; all destinations indiscriminately receive the data whether or not the data is needed by the destination computer. Where data is not needed at a particular network-connected personal computer, the transmission of the data is an inefficient use of resources. This can be particularly disabling to a network that does not have sufficient bandwidth capacity for all of the data traffic. Broadcasting is less efficient in direct relation to the proportion of users in the community, receiving a broadcast, that do not need the broadcast data.
In contrast, unicasting is a form of addressing where the destination address specifies a single destination. Unicasting eliminates the unnecessary transmission of data to destinations that have no need for the data, but is still inefficient because the data will be replicated on the network for each individual destination. For example, when data is transmitted to 20 personal computers connected to a server, 20 transmissions of the data will be made, each with a different individual destination address.
Multicasting occurs when a source sends data to a closed group of destination computers. This form of addressing is particularly beneficial where the link between the source and the server has limited capacity or high cost because only one copy of the data that is intended for multiple recipients is transmitted from the source. Multicasting makes the most efficient use of an expensive link that has insufficient capacity of transmission to multiple destinations by reducing the number of transmissions across the critical link to one, rather than requiring that multiple transmissions be made for each destination address.
The Internet, an inter-network, is an example of a communications network in which multicasting may occur. Large amounts of information have been made available for all types of use on the Internet. Multimedia applications have become common place on the World Wide Web portion of the Internet. A multimedia application is an application that uses different forms of communication in a single application. For example, information may be displayed to a user of a multimedia application on a computer using voice, text, and video simultaneously. Videos and music also may be delivered via the Internet. Multimedia applications have brought many new users to the Internet. Additionally, the Internet is widely used for obtaining information on various topics of interest. Also, numerous commercial transactions occur using the Internet.
In addition to the Internet, other communications networks for transmitting data from a source to a target or destination includes, for example, satellite based communications networks, public switched telephone networks, and local area networks. In these different types of communications networks, multiple content providers have arisen to provide content consumers data in various types and forms. With multiple content providers, it is advantageous to have an improved method and apparatus for managing transfer of data within a communications system.